The remarkable story of Leopold Socha
You have never heard of him but he is commemorated by the Yad Vashem Museum in Jerusalem (which I have visited) as “Righteous among the Nations” In the last year of Nazi occupation of Eastern Poland, he saved the lives of a group of Jews by hiding them in sewers.
The story has recently been portrayed in the Polish film “In Darkness” [see my review here] and you can read a brief account of this remarkable piece of history here.